Electronic ballast devices have been known and used in the past for fluorescent lamps. In general, conventional ballast devices of this type have not been efficient in operation because of their relatively high energy requirements. Moreover, flicker of the lamps and 60 Hertz hum have been problems with conventional ballast devices. Temperatures of the ballast device are relatively high and cooling of the ballast unit must be taken into consideration to avoid overheating problems. Because of these drawbacks, a need has arisen for an improved electronic ballast device for a fluorescent lamp to avoid the above problems and to increase the operating efficiency of the circuit containing a fluorescent lamp.
Prior U.S. patents relating to ballast devices for fluorescent lamps are as follows: Nos. 4,017,761, 4,320,253, 4,358,712, 4,375,608 and 4,378,514.